This study evaluates the influence of a thermal treatment of a basalt fiber on capillary wicking tests and in-plane permeability experiments, under several pressure differences. The impact of the treatment was characterized at three scales: microscopic, to determine the fiber surface energy; mesoscopic, to estimate an equivalent capillary pressure (Pcap) of the fabric in spontaneous impregnation; and macroscopic, to determine the saturated (Ksat) and unsaturated (Kunsat) permeability of the fibrous preform at the process scale. Results at the microscopic scale showed that the thermal treatment increased the polarity of the fiber by 22% and decreased its surface roughness. Capillary wicking tests showed that the treated fabric presents a better affinity with water, increasing Pcap by 68%. At the process scale, permeability experiments showed the increase of Ksat and Kunsat after treatment. Finally, results of capillary pressure showed a dominance of capillary effects under the negative pressure difference.